On 07/08/2019 10:29 PM, Peter Zijlstra wrote:
Thanks for the comments.
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 0ab99c7..19e6593 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -528,6 +528,7 @@ typedef void (*perf_overflow_handler_t)(struct perf_event *,
*/
#define PERF_EV_CAP_SOFTWARE BIT(0)
#define PERF_EV_CAP_READ_ACTIVE_PKG BIT(1)
+#define PERF_EV_CAP_NO_COUNTER BIT(2)
#define SWEVENT_HLIST_BITS 8
#define SWEVENT_HLIST_SIZE (1 << SWEVENT_HLIST_BITS)
@@ -895,6 +896,13 @@ extern int perf_event_refresh(struct perf_event *event, int refresh);
extern void perf_event_update_userpage(struct perf_event *event);
extern int perf_event_release_kernel(struct perf_event *event);
extern struct perf_event *
+perf_event_create(struct perf_event_attr *attr,
+ int cpu,
+ struct task_struct *task,
+ perf_overflow_handler_t overflow_handler,
+ void *context,
+ bool counter_assignment);
+extern struct perf_event *
perf_event_create_kernel_counter(struct perf_event_attr *attr,
int cpu,
struct task_struct *task,
Why the heck are you creating this wrapper nonsense?
(please see early discussions: https://lkml.org/lkml/2018/9/20/868)
I thought we agreed that the perf event created here don't need to consume
an extra counter.
In the previous version, we added a "no_counter" bit to perf_event_attr, and
that will be exposed to user ABI, which seems not good.
(https://lkml.org/lkml/2019/2/14/791)
So we wrap a new kernel API above to support this.
Do you have a different suggestion to do this?
(exclude host/guest just clears the enable bit when on VM-exit/entry,
still consumes the counter)
Best,
Wei
